保温瓶中的开水要装得浅一些,塞上木塞。这样,开水与木塞之间保留了一定厚度的空气层,由于空气是热的不良导体,所以增加了保温瓶的保温性能。如果开水装满, Thermos flask to be filled with shallow water, stuffed with cork. In this way, a certain thickness of air layer is reserved between the boiling water and the cork, which increases the heat insulation performance of the thermos because the air is an unfavorable conductor of heat. If boiled water is full,